guar

The guar bean or cluster bean (Cyamopsis tetragonolobus) is an annual legume and the source of guar gum. It grows best under conditions with frequent rainfall, but tolerates arid conditions well.^[1] 80% of world production occurs in India, but, due to strong demand, the plant is being introduced into new areas. It is known as kotthavarai (கொத்தவரைக்காய்) in Tamil.

Cultivation

For best growth, the guar bean requires full sunshine, flashing rainfalls that are moderately frequent, and well drained soil. However, it is extremely drought-tolerant and thrives in semi-arid regions. Too much precipitation can cause the plant to become more "leafy" thereby reducing the number of pods and/or the number of seeds per pod that affects the size and yield of seeds. The crop is sown after the first rains in July and harvested in late October. It is grown principally in northwestern India, and Pakistan^[2] with smaller crops grown in the semi-arid areas of the high plains of Texas in the USA^[3], Australia and Africa. The most important growing area centres on Jodhpur in Rajasthan, India.

Currently India is the source of about 80% of the world production of guar gum. Several commercial growers ^[4] have converted their crops to guar production to support the increasing demand for guar and other organic crops ^[5] in the United States.

Varieties: Pusa Naubahar and Pusa Sadabahar. Seeds at the rate of 10 to 12 kilograms/hectares (9–11 lb/acre) are planted at a spacing of 45-60 x 20-30 cm (18–24 x 8–12 in) in February-March and June-July. During rainy season, the seeds are sown 2-3 cm (~1 in) deep on ridges and in furrows during summer months. FYM is applied at the rate of 25 tonnes/ha (11.1 tons/acre). N, P2O5 and K2O recommendation for the crop is 20:60:80 kg/ha (18:53:71 lb/acre). Average yield is 5 to 6 tonnes/ha (2.2–2.6 tons/acre).

Uses

Agriculture

Guar can be fed to cattle, or used as a green manure.

Food

Guar can be eaten as a green bean, but is more important as the source of guar gum. Guar beans have a large endosperm that contains galactomannan gum, a substance which forms a gel in water. This is commonly known as guar gum and is used in dairy products like ice cream and as a stabilizer in cheese and cold-meat processing.

Another use is as a fiber supplement. After being partially hydrolyzed, guar gum is completely soluble in water and soft food. Being approximately 75% dietary fiber, it allows fiber to be added to a food with a minimal effect on taste and texture.

Partially hydrolyzed guar gum (PHGG) is produced by the partial enzymatic hydrolysis of guaran, the galactomannan of the endosperm of guar seeds (guar gum). It is a neutral polysaccharide consisting of a mannose backbone chain with single galactose side units occurring on almost two out of every three mannose units. The average molecular weight is about 25,000 Daltons. This gives a PHGG that still assays and functions as a soluble dietary fiber. PHGG as sold commercially is completely soluble, acid and heat stable, unaffected by ions, and will not gel at high concentrations. PHGG is fully fermentable in the large bowel with a high rate of volatile fatty acid formation. The pH of the feces is lowered along with an increase in fecal bulk that mainly consists of bacteria cell mass and water. Clinical studies have demonstrated a prebiotic affect of PHGG. Studies have also shown that PHGG can be used to maintain regularity. PHGG is used in foods for particulate suspension, emulsification, anti-staling, ice crystal control, and reduced fat baked goods.

Industrial uses

Derivatives of Guar gum that has been further reacted is also used in industrial applications such as the paper and textile industry, ore flotation, the manufacture of explosives and hydraulic fracturing of oil and gas formations. Guar gum has also proven a useful substitute for locust bean gum (made from carob seeds).

Sugaring paste used for epilation may include guar as an ingredient.^[6]

References

1. ^ "Guar Gum" - Agro Gums
2. ^ " Guar Gum". Midwest Herbs
3. ^ "Guar Production" Vernon Agricultural Research & Extension Center, Texas A&M Univ. 2006.
4. ^ "large scale guar growers"
5. ^ "organic fertilizer crops"
6. ^ Studio Smooth website. Accessed April 11, 2009.

Scientific Literature

• Overbeeke N, Termorshuizen GH, Giuseppin ML, Underwood DR, Verrips CT (May 1990). "Secretion of the alpha-galactosidase from Cyamopsis tetragonoloba (guar) by Bacillus subtilis". Appl. Environ. Microbiol. 56 (5): 1429–34. PMID 2160224. PMC: 184423. http://aem.asm.org/cgi/pmidlookup?view=long&pmid=2160224. 
• Bergkamp RJ, Kool IM, Geerse RH, Planta RJ (April 1992). "Multiple-copy integration of the alpha-galactosidase gene from Cyamopsis tetragonoloba into the ribosomal DNA of Kluyveromyces lactis". Curr. Genet. 21 (4-5): 365–70. PMID 1326415. 
• GOPALA RAO P, C. DAMODARA REDDY and J. K. RAMAIAH (1987). "Effect of B Vitamins on the Protein Component of Clusterbeans Cyamopsis tetragonoloba (L.) Taub". Annals of Botany 59 (3): 281–4. http://aob.oxfordjournals.org/cgi/content/abstract/59/3/281. 

External links

• The chemical, physical, and physiological properties of partially hydrolyzed guar gum